Here, owning a car is extremely expensive - perhaps one of the most expensive in Europe. This price goes up considerably when you get a larger vehicle, both because fuel costs are very high but also because you are taxed quarterly for CO2/weight of the vehicle.
With a larger family, you are squeezed into an uncomfortable position since you are outside of the <= 2 child norm. Many 7+ seater vehicles (French cars, etc) are extremely impractical to the point of me thinking that they are not actually designed for more than 5 seats in use, as there is comically low cargo room and the 3rd row is extremely cramped (try fitting a stroller or anything besides people...ha!).
I ended up picking up a Chrysler Town & Country import from the USA for my family, because it was the only vehicle that I could find for a reasonable price that checked all of the boxes, and am paying dearly for it (400+ euros every quarter just to have the privilege of registering it!).
Before you say anything about us having a "kindercrusher" we also have 2 bakfiets cargo bikes and use them regularly, but public transit and bikes don't scale well to large families for anything more than a short distance ride (school, groceries, etc).
Large families are being squeezed out of existence here.